1. Field of the Invention
The invention relates to a process for removing silicones from fibers, yarns or two-dimensional textile materials by treatment with aqueous preparations which may contain detergent substances, wetting agents and alkali carbonate, optionally at elevated temperatures.
2. Description of the Prior Art
Silicones are being increasingly used for the surface treatment of fibers, yarns, or two-dimensional textile materials. Moreover, silicones are used especially for hydrophobizing textiles. Fabrics treated with silicones acquire a soft and pliant feel. Yarns treated with silicones, especially with silicone oils, exhibit reduced fiber/metal friction.
The silicones used for these purposes are the liquid to pasty, chain-forming dialkylpolysiloxanes, especially dimethylpolysiloxanes that contain methylhydrogenpolysiloxanes which can be fixed on the fibers, as well as silicone resins which contain trifunctional silicone units and can be condensed on the fibers.
It is desirable that the organosilicones are difficult to remove from the fiber so that the silicone impregnation is resistant to laundering and dry cleaning. However, this property interferes with the stripping of the silicone impregnation which becomes necessary due to faulty batches. In "Chemie und Technologie der Silicone" (Chemistry and Technology of the Silicones) by Walter Noll, published by Verlag Chemie GmbH, 2nd edition, 1968, page 512, it is stated that the silicone films decomposed at elevated temperatures under acidic conditions. Such treatment can be combined with the use of solvent-containing detergents. However, such an aggressive procedure frequently leads to damage to the fibers.
Furthermore, it is well known that silicone impregnants can be removed from textile materials by treating the textile materials with aqueous preparations which contain detergent substances, oxalic acid and soda. While this procedure is somewhat more gentle, it does not permit complete removal of the silicones from the textile surfaces and fails especially when the silicones are crosslinked to products of high molecular weight.